Variable Responses of Zoysiagrass Genotypes to the Sting Nematode

Sting nematodes (Belonolaimus longicaudatus) can injure roots of many warm-season turfgrasses in sandy, well-drained soils and on artificial, sand-based putting greens. Resistant or tolerant grasses could reduce the need for chemical control. This research was initiated to assess the host status and relative tolerance of six warm-season genotypes-four zoysia-grasses (Zoysia Willd.), one St. Augustinegrass [Stenotaphrum secundatum (Wait.) Kuntze], and one bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davyl-to the sting nematode by two screening methodologies in sequential glasshouse trials in 2007. All entries were hosts with final sting populations 1.7 to 11.0 times greater than initial inoculation levels. Results indicate that evaluating root lengths of unestablished sprigs under sting nematode pressure may improve the identification of genotypes with greater genetic tolerance than in methods using established plants. Total root lengths were not reduced by sting nematodes in UFZ-10, indicating greater tolerance than found in other entries. Treatments of 'Empire', 'Cavalier', 'Emerald', 'TifEagle', and 'Floratam' inoculated 45 d after planting exhibited total root length reductions of 24, 29, 29, 32, and 37%, respectively, when compared with uninoculated controls. The observed variability suggests that gains from selecting for sting nematode resistance or tolerance are possible in zoysiagrass.